In vivo confocal microscopy: The role of comparative approach in patients with multiple atypical nevi

Background In vivo reflectance confocal microscopy (RCM) increases diagnostic accuracy for melanoma diagnosis when combined with dermoscopy. In patients with multiple atypical nevi, a comparative dermoscopic approach improves melanoma recognition and saves unnecessary excision. The performance of a comparative approach combining dermoscopy and RCM has not been yet investigated. Objective To validate a comparative dermoscopic + RCM approach according to melanoma diagnostic accuracy in patients with multiple atypical nevi. Methods Consecutive patients undergoing RCM examination for >= 3 atypical melanocytic lesions, assessed with a dermoscopic + RCM comparative approach in a real-life setting, from July 2012 to April 2018 at a single centre, were enrolled. Dermoscopic and dermoscopic + RCM morphologic approaches were retrospectively applied by evaluating revisited 7-point checklist, RCM and Delphi scores for each enrolled lesion. Comparative dermoscopic and dermoscopic + RCM approaches were subsequently used. For each approach, lesions were classified as non-suspicious (long-term follow-up) or suspicious (short-term follow-up or excision) and diagnostic accuracy for melanoma diagnosis was assessed. Results Diagnostic accuracy progressively increased comparing morphologic to comparative approaches, and comparing dermoscopic to dermoscopic + RCM approaches. The retrospective comparative dermoscopic + RCM approach revealed the largest area under the curve (0.84; 95%CI:0.79-0.89;P < .001) and the lowest number needed to excise (5.7). Furthermore, this approach had the highest specificity (67.6%) and sensitivity (100%) levels, which were similar to those verified in the real-life setting. The main study limitations are the retrospective design and high-risk patient inclusion only. Conclusions Comparative dermoscopic + RCM approach increases melanoma diagnostic accuracy, reducing unnecessary excision without missing melanomas.